Dexmedetomidine Reduces Response Tendency, but Not Accuracy of Rats in Attention and Short-Term Memory Tasks

• Published in: Pharmacology, biochemistry and behavior biochemistry and behavior, 1997-01, Vol.56 (1), p.31-40
• Main Authors: Ruotsalainen, Sirja, Haapalinna, Antti, Riekkinen, Paavo J., Sirviö, Jouni
• Format: Article
• Language: English
• Subjects: Adrenergic alpha-2 Receptor Agonists; Adrenergic alpha-2 Receptor Antagonists; Adrenergic alpha-Agonists - pharmacology; Adrenergic alpha-Antagonists - pharmacology; Animals; Atipamezole; Attention; Attention - drug effects; Benzylamines - toxicity; Biogenic Monoamines - metabolism; Biological and medical sciences; Brain Chemistry - drug effects; Dexmedetomidine; Drug toxicity and drugs side effects treatment; Imidazoles - pharmacology; Male; Medetomidine; Medical sciences; Memory, Short-Term - drug effects; Miscellaneous (drug allergy, mutagens, teratogens...); Neurotransmitter Uptake Inhibitors - toxicity; Noradrenergic system; Pharmacology. Drug treatments; Psychomotor Performance - drug effects; Rat; Rats; Rats, Wistar; Reaction Time - drug effects; Serial Learning - drug effects; α 2-adrenoceptors
• ISSN: 0091-3057; 1873-5177
• DOI: 10.1016/S0091-3057(96)00151-7

The present study investigated the role of α 2-adrenergic mechanisms in the performance of motor responses, attention and short-term memory in rats. A low dose (3.0 μg/kg, s.c.) of dexmedetomidine, an α 2-adrenoceptor agonist, reduced response tendency in an attentional task and a working memory task, but it did not affect the choice accuracy of rats. Atipamezole (300 μg/kg), an α 2-adrenoceptor antagonist, increased anticipatory responding. Although atipamezole did not affect the number of omissions, it reversed the effects of dexmedetomidine on that parameter. We also investigated the effects of dexmedetomidine in rats with partial destruction of noradrenergic nerves induced by the neurotoxin DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride). On its own, DSP-4 treatment did not affect choice accuracy or behavioural activity of rats in the attentional task. The effects of dexmedetomidine (0.3-3.0 μg/kg) on anticipatory responses did not differ between controls and DSP-4 group. Furthermore, the effect on omissions was not consistently diminished in DSP-4 treated rats. These results suggest that the activation of postsynaptic α 2-adrenoreceptors may be responsible for dexmedetomidine-induced reduction of response tendency while attention and short-term memory are not markedly affected.